The main character is a detective named Kuro Daijuji. His normal everyday concerns consist of somehow managing to pay the rent for his apartment and affording to eat meals. The meals are taken care of by his good friend Laika from the neighborhood orphanage, but Kuro has a harder time keeping his electricity and water connection coming (which finally runs out when he gets back from his latest free-loader meal at Laika's orphanage). However, it seems as though Kuro's luck has finally changed when the young president of Hadou Enterprises, Ruri Hadou, offers him a job to find a Grimoire to power Hadou's trump card against the terrorist organization Black Lodge: Demonbane. Despite personal objections to looking for the Grimoire, Kuro takes the job in exchange for a hefty fee offered by Ruri. Instead, the number of Kuro's problems increases when he saves Al Azif, the human form of the Grimoire Necronomicon from the clutches of Doctor West of Black Lodge. In the battle, Kuro and Al fall into the depths of Arkham City where they find Demonbane....